To reach the Federation of Black Cowboys headquarters at Cedar Lane Stables, you take the A train for about an hour out of Manhattan to the Grant Avenue station in Howard Beach, walk a mile past park-and-ride lots and construction sites and a truck selling Polish sausage, then look for the wooden rail fencing around a long and narrow stretch of trees and trailers alongside Linden Boulevard. For two decades, until the city closed the stables this year, these 26 acres of pasture, trees, and western-themed corrals provided a place for city kids to learn to ride a horse or see a rodeo.